This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A131715 #13 Dec 12 2023 09:15:44
%S A131715 0,2,4,0,-6,8,0,-2,-4,0,6,-8,0,2,4,0,-6,8,0,-2,-4,0,6,-8,0,2,4,0,-6,8,
%T A131715 0,-2,-4,0,6,-8,0,2,4,0,-6,8,0,-2,-4,0,6,-8,0,2,4,0,-6,8,0,-2,-4,0,6,
%U A131715 -8,0,2,4,0,-6,8,0,-2,-4,0,6,-8,0,2,4,0,-6,8,0,-2,-4,0,6,-8,0,2,4,0,-6,8,0,-2,-4,0,6,-8,0,2,4,0,-6,8,0,-2,-4
%N A131715 Period 12: repeat 0,2,4,0,-6,8,0,-2,-4,0,6,-8.
%H A131715 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, -1).
%t A131715 LinearRecurrence[{0, 0, 0, 0, 0, -1},{0, 2, 4, 0, -6, 8},105] (* _Ray Chandler_, Aug 08 2015 *)
%t A131715 PadRight[{},120,{0,2,4,0,-6,8,0,-2,-4,0,6,-8}] (* _Harvey P. Dale_, Sep 18 2018 *)
%K A131715 sign,easy
%O A131715 0,2
%A A131715 _Paul Curtz_, Sep 14 2007
%E A131715 Definition corrected by _Paolo P. Lava_, Jul 03 2008